Background. FORECAST is a prospective longitudinal cohort study exploring mechanism-based prognostic factors for pain persistence in sciatica. Here, we share an update on this largest deeply-phenotyped primary care sciatica cohort. Methods/results. Our cohort includes 180 people with sciatica (score >4 on Stynes’ Sum Score), aged 18–85, within 3 months of symptom onset. Psychosocial factors, self-reported sensory profiling, clinical examination, quantitative sensory testing (QST), biological samples (blood and skin samples), and Magnetic Resonance Neurography of lumbar nerve roots were collected at baseline. Pain persistence was determined at three and twelve months with the Sciatica Bothersomeness Index (SBI) and a numeric pain rating scale (NRS) as primary outcomes. Recruitment nears completion, with 160 participants enrolled to date. 127 and 96 participants have completed 3 and 12 months follow-up respectively. Overall, 56% of our cohort are female, with a mean age (SD) of 54.14yrs (16.57). Ethnicity data approximates local populations. SBI at baseline was (median [IQR]) 13[10-17], and interim longitudinal data shows stepwise improvement at 3 and 12 months. Baseline ‘average’ pain intensity was 5.56 (2.15) for leg pain, and 4.14(2.82) for low back pain (LBP). Overall, pain scores decreased at 3 and 12 months, with greater reductions in leg pain than LBP at 12 months. However, around 55–80% and 40–65% of people reported persistent pain at 3 and 12 months respectively. Conclusion. Leg pain severity was moderate and higher than LBP at baseline. All primary outcome measures demonstrate improvement over time, however 40–65% of patients report persistent pain at 12 months. Conflicts of interest. LR: Paid facilitation of post-graduate courses internationally. SK, MT, FP, KM, WS, CP, CR, SC: No conflicts of interest. GC: Editor in Chief of Health Psychology Review. Director of board of directors, MentalCHealth Care setting NoordWestVlaanderen. JF: Copyright holder of ODI (Oswestry Disability Index). Served on a data monitoring committee for a clinical trial of 2 different surgical approaches to cervical disc herniation (FORVAD). Member of HTA Prioritisation Committee B: Inside hospital Care from 2015-February 2019. Member of HTA Interventional Procedures Panel from 2010–2015. Trustee and board member of 3 spine related charities – Back to Back; British Scoliosis Research Foundation and BackCare. Expert instructed by both claimant and defendant solicitors in negligence and person injury cases. GB: Paid consultancy (RNA-seq) with Ivy Farm and Coding.bio. ABS: Paid post-graduate lecturing internationally. Co-chair NeupSig sciatica working group (unpaid). Sources of funding. This project is funded by UKRI and Versus Arthritis as part of the UKRI Strategic Priorities Fund (SPF) Advanced Pain Discovery Platform (APDP), a co-funded initiative by UKRI (MRC, BBSRC, ESRC), Versus Arthritis, the Medical Research Foundation and Eli Lilly and Company Ltd (Grant MR/W027003/1). Additional funding has been received from the back to back charity to expand longitudinal components of the study. LR has received support with PhD fees from the CSP charitable trust. ABS is supported by a Wellcome Trust Clinical Career Development Fellowship. (222101/Z/20/Z). WS is partly funded through the National Institute for Health and Care Research (NIHR) Biomedical Research Centre at the South London and Maudsley NHS Foundation Trust and King's College London. FP is funded by a Dorothy Hodgkin Career Development Fellowship in Chemistry in association with Somerville College. GB is supported by the Wellcome Trust (223149/Z/21/Z) and Diabetes UK (19/0005984). GC and KRM are partly funded by UKRI and Versus Arthritis as part of the Advanced Pain Discovery Platform (APDP) PAINSTORM (MR/W002388/1). The UKRI and Versus Arhthritis (APDP) are the major funders of FORECAST. All other funders provided either some people support, or funded projects with legacy data that we reuse

Background. Involving research users in setting priorities for research is essential to ensure research outcomes are patient-centred and to maximise research value and impact. The Musculoskeletal (MSK) Disorders Research Advisory Group Versus Arthritis led a research priority setting exercise across MSK disorders. Methods. The Child Health and Nutrition Research Initiative (CHRNI) method of setting research priorities with a range of stakeholders were utilised. The MSKD RAG identified, through consensus, four research Domains: Mechanisms of Disease; Diagnosis and Impact; Living Well with MSK disorders and Successful Translation. Following ethical approval, the research priority exercise involved four stages and two surveys, to: 1) gather research uncertainties; 2) consolidate these; 3) score uncertainties using agreed criteria of importance and impact on a score of 1–10; and 4) analyse scoring, for prioritisation. Results. The first survey had 209 respondents, who described 1290 research uncertainties, which were refined into 68 research questions. 285 people responded to the second survey. The largest group of respondents represented patients and carers, followed by researchers and healthcare professionals. A ranked list was produced, with scores ranging between 12 and 18. Key priorities included developing and testing new treatments, better targeting of treatments, early diagnosis, prevention and better understanding and management of pain, with an emphasis on understanding underpinning mechanisms. Conclusions. For the first time, we have summarised priorities for research across MSKD, from discovery science to applied clinical and health research, including translation. We present a call to action to researchers and funders to target these priorities. Conflict of Interest: None. Sources of funding: We thank the funder, Versus Arthritis for their support of the research advisory groups and this activity

Purpose and background. Understanding patients’ expectations of back pain treatment can help improve their experiences, adherence and outcomes. Patients typically expect a diagnosis and exercise-based physiotherapy, but often undervalue the role of psychological factors. This study explored patients’ expectations of outpatient physiotherapy treatment for back pain in primary care. Methods and Results. The design, a secondary analysis of a qualitative cross-sectional study, involved 25 patients (13M:12F), aged 20–81, referred with low back pain (duration 7 weeks to 9 years). This sample did not include patients with serious spinal pathologies, known psychological disorders, or those unable to communicate without assistance. Face-to-face interviews were undertaken in patients’ homes, which were audio-recorded, transcribed verbatim and analysed using the six stages of thematic analysis outlined by Braun and Clarke. Patients expected a caring clinician and a strong therapeutic relationship, where they felt believed, openly communicated with and valued as an individual. Most patients expected a diagnosis and credible explanation for their pain. There was an almost equal split between those keen to take responsibility for their care and those who felt this was the clinicians’ role. Expectations of passive therapies were slightly higher in this study than existing research. Most patients were realistic about outcomes and expected treatment to reduce their pain, but not cure it. Conclusion. A positive experience mattered most to patients, valuing the relational aspects of their care more than the clinical content provided. Patients saw back pain through a biomedical lens, and most failed to recognise the role of psychosocial factors in their condition or treatment. Conflicts of interest. None. Sources of funding. Funding for primary data: Arthritis Research UK (now Versus Arthritis)

Statement of purpose of study and background. As the treatment of low back pain (LBP) continues to evolve, there is greater recognition of the importance of optimising the therapeutic relationship to better deliver improved patient outcomes. Contextual effects, such as communication, have been shown to influence the therapeutic relationship, but it is not known how these factors evolve over time. This study analysed interviews from two studies (one cross-sectional and one longitudinal) to explore patients’ and physiotherapists’ perspectives of treatment outcomes and experiences in episodes of LBP in the same dialogic space. The objective was to explore the alignment between these perceptions to identify factors that influence the therapeutic relationship over time. Summary of methods used and results. Two secondary thematic analyses were undertaken, one analysing cross-sectional data and the other analysing longitudinal data, from an existing data set from the programme: “Exploring the relationship between communication and clinical decision-making in physiotherapy consultations for back pain”. All data were thematically analysed and organised using a framework approach. Six themes emerged from the cross-sectional data reporting consistency of opinion in the initial consultation stages, but highlighting inadequate patient involvement in shared decision making. Four main themes emerged from the longitudinal data, all of which reported interactional fears and anxieties identified on both the parts of the patient and the physiotherapist. Conclusion. These findings suggest that failing to involve the patient in adequately personalised treatment from the initial consultation may lead to diagnosis hunting and stereotyping behaviours within the therapeutic relationship, in turn leading to increased health resource usage. Conflicts of interest. None. Sources of Funding. The primary data set was collected in a research programme funded by Arthritis Research UK (now Versus Arthritis)

Background and study purpose. Low back pain with no identified underlying cause is categorised as primary musculoskeletal pain by the International Association for the Study of Pain. In April 2021, the National Institute for Care and Excellence (NICE) published updated guidance for the management of primary chronic pain conditions in England. As part of the De-STRESS pain study, we explored the perspectives of GPs on the updated guideline and impact upon clinical practice. Methods and results. Semi-structured interviews were conducted with 21 GPs in England. Data were analysed using thematic analysis and constant comparison techniques. GPs agreed with the recommendations restricting pharmacological options for pain management and reflected that they now had an expert reference to back-up their decision-making and could use the guidance in potentially difficult conversations with patients. Frustration was expressed by GPs about the lack of alternative options to medication, as the non-pharmacological recommendations were difficult to implement, had lengthy waiting lists, or were unavailable in their locality. Conclusion. Although GPs discussed benefits of the updated NICE guideline in potentially reducing prescriptions of ineffective and potentially harmful medications, frustration about the lack of alternative strategies added to the difficulties encountered in managing people with persistent back pain in primary care. Conflicts of interest: No conflicts of interest. Sources of funding: This study was funded by Versus Arthritis – grant number 22454; Carolyn A Chew-Graham is part-funded by NIHR Applied Research Collaboration (ARC) West Midlands

Background and study purpose. Low mood and distress are commonly reported with by people with persistent musculoskeletal pain and may be mislabelled as ‘depression’. In order to understand how pain-related distress is conceptualised and managed in primary care consultations, we explored understanding of pain-related distress and depression from the perspectives of people with persistent musculoskeletal pain and general practitioners (GPs). Method and results. Semi-structured interviews with 21 GPs and 21 people with persistent musculoskeletal pain were conducted. The majority of people with pain had back pain (15/21). Data were analysed thematically using constant comparison techniques. Participants described challenges distinguishing between distress and depression in the context of persistent pain but described strategies to make this distinction. Some people with pain described how acceptance of their situation was key, involving optimism about the future and creation of a new identity. Some GPs expressed ‘therapeutic nihilism’, with uncertainty about the cause of pain and thus how to manage people with both pain and distress, whilst GPs who could identify and build on optimism with patients described how this could help the patient to move forwards. Conclusion. This study offers a model for the primary care consultation with patients presenting with pain-related distress. GPs should recognize the impact of pain on the patient, support the person in acceptance of the pain, explore how the person feels about the future, encourage optimism, and support self-management strategies. Conflicts of Interest: No conflict of interests. Sources of funding: This study was funded by Versus Arthritis – grant number: 22454; Carolyn A Chew-Graham is part-funded by NIHR Applied Research Collaboration (ARC) West Midlands

Background. We have previously reported an injectable hydrogel (NPgel), which could deliver patients own stem cells, via small bore needles, decreasing damage to the annulus fibrosus. NPgel drives differentiation to NP cells and can inhibit the degenerate niche. However, clinical success of NPgel is dependent on the capacity to inject NPgel into naturally degenerate human discs, restore mechanical function to the IVD, prevent extrusion during loading and induce regeneration. This study assessed injectability of NPgel into human IVD, influence on mechanical properties, regeneration ability in an ex vivo culture system and retention under failure testing. Methodology. Cadaveric human discs were used to calculate disc height and to determine Youngs Modulus during simulated walking pre and post injection of NPgel, extrusion testing performed. Whole human IVDs were injected with NPgel +/− human BMPCs and maintained in culture under physiological loading regime for 4 weeks. Pre and post culture MRI imaging and in line biomechanical characteristics determined. Histology and immunochemistry performed for anabolic and catabolic factors. Results. NPgel injection significantly increased disc height and Youngs modulus with no extrusion observed during failure testing. T1ρ intensity was increased during culture in those injected with NPgel +/− cells compared to non-injected discs, and biomechanical restoration. Histological analysis has demonstrated excellent tissue attachment to the injected gel, and cellular migration into acellular gel systems. With increased matrix production and decreased catabolic factor expression. Conclusion. These results provide essential proof of concept data supporting the use of NPgel as an injectable therapy for disc regeneration. Conflict of interest: C Le Maitre & C Sammon are inventors on the hydrogel discussed. Funding: This work was funded by MRC and Versus Arthritis

Background. Free From Pain (aka Fear Reduction, Exercise Early with Food from plants, Rest and relaxation, Organisation and Motivation to decrease Pain from Arthritis and Increase Natural Strength) is a functional rehabilitation programme to combat sarcopenia and musculoskeletal pain in seniors. It is also published as a book (ISBN-0995676941). The aim of this audit was to evaluate the safety and suitability of the exercises and the usefulness of the exercise book. Methods and Results. Participants were volunteers who paid to attend the Free From Pain Exercise programme. Participants evaluated the exercises using a 5-point Likert scale and the Exercise Book using the Usefulness Scale for Patient Information Material (USE). 30 participants attended the Free From Pain programme. 26 participants completed the questionnaire. This included 20 females and 6 males, with a mean age of 76 years. The mean scores on the 0 to 5 Likert scales were A) Exercises were suitable? 4.69; B) Exercises were safe? 4.58; C) Absence of any injury or medical event whilst exercising? 4.58; D) Covered all body parts? 4.38; E) Easy to do at home? 4.42; F) Encouraged to do more exercise? 4.42; G) Recommend to family and friends? 4.50. The mean scores of the cognitive, emotional, and behavioural sub domains of the USE scale, scored 0 to 30, were 25.23, 23.73 and 23.69, respectively. Conclusion. The pre-pilot study suggests that the suggested exercises are safe and suitable for seniors, and that the exercise book is holistically useful. Conflict of Interest: G Ampat sells the Free From Pain Exercise book online through Amazon and other platforms. S Rhodes and J Sims are employed by Talita Cumi Ltd, of which Free From Pain is a trading name. Jacqueline Howard is a medical student and has no conflict of interest. Sources of funding: No funding was obtained

Background. Trunk muscle activity and thoraco-lumbar kinematics have been shown to discriminate non-specific chronic low back pain (NSCLBP) subgroups from healthy controls. Thoracic spine kinematics and muscle activity whilst intuitively associated with NSCLBP, has received less attention and the possibility of intra-regional interactions remains an area for exploration. Purpose. Determine relationships between muscle activation and kinematics in active extension pattern (AEP) and flexion pattern (FP) subgroups and no-low back pain controls during a sagittal bending task. Methods. Fifty NSCLBP subjects (27 FP, 23 AEP) and 28 healthy controls underwent 3D motion analysis (Vicon™) and surface electromyography whilst bending to retrieve a pen from the floor. Mean sagittal angle for the upper and lower thoracic and lumbar regions (UTx, LTx, ULx, LLx) were compared with normalised mean amplitude electromyography of 4 bilateral trunk muscles. Pearson correlations were computed to assess relationships. Results. Significant relationships between lumbar multifidus and ULx/LLx were identified in AEP during bending and return (p<0.01). FP exhibited multiple significant interactions including between longissimus thoracis and lumbar multifidus and LLx/LTx (p<0.035); and external oblique activity and UTx/LTx (p<0.05) during bending and return (and LLx during bending). Correlations were moderate to strong (r= −0.812 to 0.664). Conclusion. Kinematic and trunk muscle activity measurements differentiated between NSCLBP sub-groups and controls, especially between LLx kinematics and lumbar multifidus activity. Contrasting muscle activation patterns between LLx and LTx regions in FP highlights the importance of regional thoracic measurements, and suggests likely compensation strategies. Replication during other tasks should be evaluated in future studies. No conflicts of interest. Funding provided by Versus Arthritis (Formerly Arthritis Research UK)

Introduction. Injectable hydrogels via minimally invasive surgery reduce the risk of infection, scar formation and the cost of treatment. Degradation of the intervertebral disc (IVD) currently has no preventative treatment. An injectable hydrogel material could restore disc height, reinforce local mechanical properties, and promote tissue regeneration. We present a hydrogel material Laponite. ®. associated poly(N-isopropylacrylamide)-co-poly(dimethylacrylamide) (NPGel). Understanding how the components of this hydrogel system influence material properties, is crucial for tailoring treatment strategies for the IVD and other tissues. Methods & Results. The effect of hydrogel wt./wt., clay and co-monomer percentages were assessed using a box-Behnken design. Rheometry, SEM, FTIR and swelling was used to measure changes in material properties in simulated physiological conditions. Rheometry revealed gelation temperature of hydrogel materials could be modified with dimethyl-acrylamide co-monomer; however, final maximum mechanical properties remained unaffected. Increasing the weight % and clay % increased resultant mechanical properties from ∼500–2500 G' (Pa), increased viscosity, but retained the ability to flow through a 26G needle at 39°C. Discussion & Conclusions. By increasing the weight and clay percentage of the material we can attain greater mechanical properties, this could be beneficial for orthopaedic or even dental applications. By modifying the co-monomer percentage, we can control gelation temperature important for ensuring the material is fully set at 37°C, this could also be utilised to locally deliver drugs from the implanted material. Our current work is focused on comparing our NPGel material formulation with human IVD tissue. Acknowledgements. We would like to thank Arthritis Research UK grant number 21497 for supporting this research. No conflicts of interest. Sources of Funding: Funded by Arthritis Research UK grant number 21497

Aims

To investigate the correlations among cytokines and regulatory T cells (T-regs) in ankylosing spondylitis (AS) patients, and their changes after anti-tumour necrosis factor-α (TNF-α) treatment.

Aims

Symptomatic spinal stenosis is a very common problem, and decompression surgery has been shown to be superior to nonoperative treatment in selected patient groups. However, performing an instrumented fusion in addition to decompression may avoid revision and improve outcomes. The aim of the SpInOuT feasibility study was to establish whether a definitive randomized controlled trial (RCT) that accounted for the spectrum of pathology contributing to spinal stenosis, including pelvic incidence-lumbar lordosis (PI-LL) mismatch and mobile spondylolisthesis, could be conducted.

Introduction. Low back pain is the leading cause of musculoskeletal disease and the biggest cause of morbidity worldwide. Approximately 40% of these are cases are caused by disease of the intervertebral discs (IVDs): the shock absorbing, flexible material located between the bones (vertebrae) along the length of the spine. In severe cases, the spine becomes unstable and it becomes necessary to immobilise or fix the joint in position using a lumbar cage spacer between in the IVD and metal pins with supporting plates in the vertebrae. This is a complex, expensive, major surgery and it is associated with complications, such as spinal fusion failure and inappropriate implant position. These complications have a dramatic impact on the quality of life of the affected patients and the burden to society and the healthcare system is exacerbated. Methods and Results. We present an in vitro study looking at the effect of our Bgel hydrogel on mesenchymal stem cells (MSCs) and their bone forming capacity within lumbar cages: devices used to space the bones apart in the fusion operation, as a mechanism to improve fixation and intra cage bone formation. MSCs were isolated from human hip joint, expanded, seeded within Bgel, cast into well inserts or lumbar cages and cultured for 4 weeks. Using 3D X-ray imaging micro computed tomography (μCT) scans we show that the MSC in the presence Bgel begin to mineralise within the lumbar cages. Histology is currently ongoing and will be presented at the meeting. Conclusion. This study shows the potential to improve current spinal fusion practices with the potential to reduce complications. Conflicts of interest: CS and CLM are named inventors on the patent for NPgel/BGel. Funded by the Medical Research Council and Versus Arthritis UK: SNiPER

Purpose of the study and background. The preliminary study aimed to establish clinical and research expert opinion with regards to the key components of an assessment of a person with Mechanical Low Back Pain (MLBP). We aimed to identify the key subjective questions and objective tests which would be helpful for clinicians to develop the most appropriate self-management exercise programme. This is the first part of the study to develop the ‘Back-to-Fit’ digital tool offering personalised self-management exercise solutions for people with MLBP. Summary of the methods. A Bristol online survey which included a questionnaire with a series of open and closed questions was developed using the literature and was distributed among clinicians/researchers with a background in the clinical management of MLBP. The questionnaire included 6 demographic questions followed by sections related to subjective questions and objective tests of the MLBP assessment. 71 participants responded to the survey. Results. In the subjective assessment component, ≥80% level of agreement was obtained for 17 of 26 proposed subjective questions and 05 of the 21 suggested objective tests. Two more questions and two objective tests to be included in the assessment had been suggested by the partcipants. Conclusion. These expert agreements on questions and opinions provides an indication of the key subjective and objective components to be included in a self-assessment tool in a personalised self-management platform for MLBP. Further testing with a multiple round Delphi study in a large sample of experts is now required to obtain consensus for the above findings. Conflicts of interest: No conflicts of interest. Sources of funding: Biomechanics and Bioengineering Research Centre Versus Arthritis, Cardiff University, UK

Purpose of study and background. We have previously reported the development of injectable hydrogels for potential disc regeneration (NPgel) or bone formation which could be utilized in spinal fusion (Bgel). As there are multiple sources of mesenchymal stem cells (MSCs), this study investigated the incorporation of patient matched hMSCs derived from adipose tissue (AD) and bone marrow (BM) to determine their ability to differentiate within both hydrogel systems under different culture conditions. Methods and Results. Human fat pad and bone marrow derived MSCs were isolated from femoral heads of patients undergoing hip replacement surgery for osteoarthritis with informed consent. MSCs were encapsulated into either NPgel or Bgel and cultured for up to 6 weeks in 5% (NPgel) or 21% (Bgel) O. 2. Histology and immunohistochemistry was utilized to determine phenotype. Both fat and bone marrow derived MSCs, were able to differentiate into both cell lineages. NPgel culture conditions increased expression of matrix components such as collagen II and aggrecan and NP phenotypic markers FOXF1 and PAX1, whereas Bgel induced expression of collagen I and osteopontin, indicative of osteogenic differentiation. Conclusion. NPgel and Bgel were able to differentiate patient derived MSCs from different sources into both NP and osteogenic lineages, which may give rise to novel treatment strategies for IVD degeneration and spinal fusion, enabling choice for cell source according to patients' circumstances and needs. C Le Maitre and C Sammon hold a patent for the hydrogel described. Funded by MRC and Versus Arthritis

Introduction. Musculoskeletal diseases are the biggest cause of morbidity worldwide, with low back pain (LBP) being the leading cause. Forty percent of LBP cases are caused by disease of shock absorbers in the spine known as intervertebral discs (IVDs). The IVDs enable the spine to twist and bend, whilst absorbing load during normal daily activities. The durability of this tissue is sustained by the cells of the spine and so during disease or mechanical damage these cells can behave abnormally further damaging the disc and stimulating local nerves causing extreme pain. Degradation of the intervertebral disc (IVD) currently has no preventative treatment; an injectable hydrogel biomaterial could reinforce disc mechanical properties and promote tissue regeneration. Methods and Results. We present an injectable range of hydrogel biomaterials made from water, clay and polymer that set at 37°C. The materials were made at 80°C polymerised in water and stored at 70°C to remain liquid. The physical properties of the materials were assessed using various methods, including mechanical assessment using temperature-controlled rheometry to monitor the liquid-hydrogel transition. Conclusion. Results showed that by changing three factors within the formulation we can produce a range of materials with suitable mechanical and morphological properties for a variety of tissues of the spine. These types of biomaterials have the potential to provide the first efficacious early-mid stage treatment for IVD disease and reduce the cost of LBP on our health services. Conflicts of interest: CS and CLM are named inventors on the patent for NPgel/BGel. Funded by the Medical Research Council and Versus Arthritis UK: SNiPER

Introduction. Injectable hydrogels via minimally invasive surgery offer benefits to the healthcare system, reduced risk of infection, scar formation and the cost of treatment. Development of new treatments with the use of novel biomaterials requires significant pre-clinical testing and must comply with regulations before they can reach the bedside. In the European economic area (EEA) one of the first hurdles of this process is attaining the CE marking which protects the health, safety and environmental aspects of a product. Implanted materials fall under the class III medical device EU745 regulation standards. To attain the CE marking for a product parties must provide evidence of the materials safety with an investigational medicinal product dossier (IMPD). Methods and Results. We have been working to develop a new thermoresponsive injectable biomaterial hydrogel (NPgel) for the treatment of intervertebral disc (IVD) disease. A large part of the IMPD requires information on how the hydrogel physical properties change over time in bodily conditions. We have been studying 6 batches of NPgel over 18 months, tracking the materials wet/ dry weight, structure and composition. To date we have found that NPgel in liquids more similar to the body (with protein and salts) appear to be stable and safe, whilst those in distilled water swell and disintegrate over time. Subtle long-term changes to the material composition were found and we are currently investigating its ramifications. Conclusion. The study highlights the need to test materials in detail in physiologically representative environments before approaching the bedside and demonstrates promise for NPgel as a suitable CE candidate. Conflicts of interest: CS and CLM are named inventors on the patent for NPgel/BGel. Funded by the Medical Research Council and Versus Arthritis UK: SNiPER

Purpose of study and background. Mechanical overloading initiates intervertebral disc degeneration, presumably because cells break down the extracellular matrix (ECM). We used Fourier Transform Infrared Spectroscopy (FTIR) imaging to identify, visualize and quantify the ECM and aimed to identify spectroscopic markers for early disc degeneration. Methods and Results. In seven goats, one disc was injected with chondroitinase ABC (mild degeneration) and after three months compared to control. Ex vivo, 50 caprine discs received physiological loading (50–150N) or overloading (50–400N) in a loaded disc culture system. To determine whether ECM degeneration is due to cell activity, half of the discs was subjected to freeze-thaw cycles. Spectroscopic images were collected at 1000–1300 cm. −1. and analyzed using multivariate curve resolution analysis. In vivo, less proteoglycan was found in the degenerated group (p<0.05), especially in the nucleus. Collagen content was increased in the nucleus and anterior annulus, and had higher entropy (p<0.01), indicating matrix disorganization. In the ex vivo experiment, the proteoglycan/collagen ratio was decreased (p<0.05) in the vital group and there was an increase in collagen entropy (p<0.05). A significant interaction between loading and vitality was found in the amount of collagen (p<0.05), but not in the entropy. Conclusion. Three weeks of mild overloading causes measurable changes in the extracellular matrix. Increased collagen entropy indicates that remodeling of collagen is a first step into disc degeneration. We could not confirm, however, that increase in entropy was due to cell activity. FTIR imaging allows more detailed investigation of early disc degeneration than traditional measures. There are no conflicts of interest. Partially funded by Dutch Arthritis Funds, personal grant KSE

Objective. Modic changes (MC) is a form of intervertebral disc degeneration visible as subchondral and vertebral bone marrow changes on spine magnetic resonance (MR). Their etiology is not understood, but microbial infection may be involved for some subtypes. This study set out to test for an association between MC and gut microbiome in a population sample. Methods. Presence of MC was evaluated in lumbar MR images and gut microbiome assessed using 16S sequencing in TwinsUK dataset (N=309). Cases were identified by the presence of MC of any type, while controls were those without MC. Amplicon sequence variants (ASVs) have been obtained for 16S sequences followed by relative abundance calculation and centred log-ratio transformation. Linear mixed-effects models were applied to test for association between the ASVs at different taxon levels and MC adjusting for technical covariates and demographics. Results. Nominally significant (p<0.05) associations with MC were obtained for 6 ASVs annotated to species level (min p = 0.0016 for Sanguibacteroides justesenii), 8 ASVs annotated to genus level (min p = 0.0091 for Syntrophomonas), and 2 ASVs annotated to family level (min p = 0.0099 for Syntrophomonadaceae). None of the associations were significant after correction for multiple testing. Also, no statistically significant difference in microbial diversity was found between MC cases and controls. Conclusions. The results of this pilot study provide limited evidence of association between MC and gut microbiome. Further studies including MC stratified by subtype are warranted as well as studies based on advanced metagenome sequencing rather than 16S approach. No conflicts of interest. The study was supported by Versus Arthritis grant # 21227

Purpose of study and background. Low back pain affects 80% of the population at some point in their lives with 40% of cases attributed to intervertebral disc (IVD) degeneration. A number of potential regenerative approaches are under investigation worldwide, however their translation to clinic is currently hampered by an appropriate model for testing prior to clinical trials. Therefore, a more representative large animal model for IVD degeneration is needed to mimic human degeneration. Here we investigate a caprine IVD degeneration model in a loaded disc culture system which can mimic the native loading environment of the disc. Methods and Results. Goat discs were excised and cultured in a bioreactor under diurnal, simulated-physiological loading (SPL) conditions, following 3 days pre load, IVDs were degenerated enzymatically for 2hrs and subsequently loaded for 10 days under physiological loading. A PBS injected group was used as controls. Disc deformation was continuously monitored and changes in disc height recovery quantified using stretched-exponential fitting. Histological staining was performed on caprine discs to assess extracellular matrix production and immunohistochemistry performed to determine expression of catabolic protein expression. The injection of collagenase and cABC induced mechanical behavior akin to that seen in human degeneration. A decrease in collagens and glycosaminoglycans (GAGs) was seen in enzyme injected discs, which was accompanied by increased cellular expression for degradative enzymes and catabolic cytokines. Conclusion. This model provides a reproducible model of IVD degeneration which mimics human degeneration. This model allows the testing of biomaterials and other potential treatments of IVD degeneration on a scale more representative of the human disc. There are no conflicts of interest. Funded by MRC and Versus Arthritis